Recently, along with the continuous development of office automation, such household display devices as personal computers and flat-panel computers have been widely used in our daily lives so as to learn and acquire information. These computers have become an indispensable part of our lives.
However, it is impossible for a display device of the computer available on the market to be automatically adjusted in such a manner as to enable a user to be in an optimum viewing arrange. Usually, the user needs to hold a posture for a long time period, so as to be adapted to an image displayed on the display device. Although the display devices for some desktop computers may be manually rotated forwardly and backwardly by a certain angle so as to be adapted to a user's sitting posture, it is difficult for the user to keep realizing when the sitting posture needs to be adjusted, and whether or not a distance between the display device and the user is optimum or whether or not the sitting posture is unhealthy. Hence, in the case that the distance between the display device and the user is inappropriate or the sitting posture is incorrect, the user may easily feel visual fatigue, and even the health of the user may be adversely affected.